CN111944477B

CN111944477B - Heat-conducting type bi-component pouring sealant and preparation method thereof

Info

Publication number: CN111944477B
Application number: CN202010848708.8A
Authority: CN
Inventors: 姬振行; 王少华; 张海凤; 王宇川
Original assignee: Cetc Baoli Beijing Technology Co ltd
Current assignee: Cetc Baoli Beijing Technology Co ltd
Priority date: 2020-08-21
Filing date: 2020-08-21
Publication date: 2021-03-26
Anticipated expiration: 2040-08-21
Also published as: CN111944477A

Abstract

The invention provides a heat-conducting type bi-component pouring sealant which is composed of a component A and a component B, wherein the component A comprises the following raw materials in parts by weight: 40-70 parts of vinyl silicone oil, 12-17 parts of modified heat-conducting filler, 8-15 parts of reinforcing filler, 0.5-1 part of catalyst, 0-11 parts of polyether modified silicone oil and 0-20 parts of dimethyl silicone oil; the component B comprises the following raw materials in parts by weight: 30-50 parts of vinyl silicone oil, 13-22 parts of hydrogen-containing silicone oil, 12-17 parts of modified heat-conducting filler, 6-11 parts of polyether modified silicone oil, 0.5-1 part of inhibitor, 0-11 parts of polyether modified silicone oil and 0-20 parts of dimethyl silicone oil; the conditions are that in the A, B component, the total amount of the dimethyl silicone oil is 15-20 parts, and the total amount of the polyether modified silicone oil is 6-11 parts; the modified heat-conducting filler is prepared from a macromolecular coupling agent and an inorganic heat-conducting filler. The pouring sealant can reduce the using amount of the inorganic heat-conducting filler, and the heat conductivity of the cured material is still excellent. Meanwhile, the weather resistance, the light transmittance, the mechanical property and the leveling property can meet the requirements.

Description

Heat-conducting type bi-component pouring sealant and preparation method thereof

Technical Field

The invention belongs to the field of adhesives, and particularly relates to a heat-conducting type bi-component pouring sealant and a preparation method thereof.

Background

The pouring sealant is used for bonding, sealing, encapsulating and coating protection of electronic components. The pouring sealant is liquid before being cured, has fluidity, and the viscosity of the glue solution is different according to the material, the performance and the production process of the product. The potting adhesive can play the roles of water resistance, moisture resistance, dust prevention, insulation, heat conduction, confidentiality, corrosion resistance, temperature resistance and shock resistance after being cured. The electronic potting adhesive has many types, and is classified by material type, and the most common types used are mainly 3 types, namely epoxy resin potting adhesive, organic silicon resin potting adhesive and polyurethane potting adhesive. The two-component silicon pouring sealant has moderate operable time because of no quick gel, can be quickly cured once heated, has no by-product during curing, has no shrinkage, has excellent insulating property and high temperature and low temperature resistance, is often used for the pouring of electronic and electrical elements, and improves the service performance and stability parameters; and transparent silica gel becomes transparent elastomer after the vulcanization, and is clearly visible to the components and parts packaged in the glue layer, can observe component parameters, and is convenient for detect and repair.

With the development of industrial production and scientific technology, higher requirements are put forward on the thermal conductivity of the pouring sealant, and due to the rapid development of integration technology and assembly technology in the field of electrical and electronic, the volumes of electronic elements and logic circuits are reduced by tens of thousands of times, and high heat dissipation, moisture resistance and dust resistance are required. Although the types of heat-conducting potting materials are many, the condensed heat-conducting potting adhesive is not environment-friendly because small molecules such as acetone, ethanol and the like can be removed; most addition type organic silicon pouring sealants mainly focus on the research on the aspect of high heat conduction, and the research on the aspects of self-leveling property and bonding property is slightly insufficient. In addition, the self-bonding heat-conducting pouring sealant has poor weather resistance after being formed, an adhesive layer is easy to oxidize and deteriorate, inorganic filler is likely to be separated out from the composite material, and the excellent properties and functions of the pouring sealant cannot be effectively maintained after long-term placement.

At present, the main method for solving the heat conduction problem of the addition type organic silicon pouring sealant is to add a heat conduction agent, and the main method for solving the addition type bonding problem is to add some functional group-containing auxiliary agents, such as a base coating agent and the like.

CN110804278A discloses a heat-conducting insulating epoxy potting adhesive, which comprises 20-30 parts of epoxy resin, 80-100 parts of high-heat-conducting inorganic filler, 100-120 parts of ethyl acetate and a small amount of other auxiliary materials. Wherein the inorganic filler is aluminum nitride, boron nitride or silicon carbide. After this patent has added heat conduction filler, the casting glue solidification back, and the heat conductivity has obtained improving, but inorganic filler addition is too much, and the compatibility of inorganic filler and organosilicon is not good on the one hand, and after long-time the putting back, inorganic filler has slowly to separate out from the casting glue, and the trend of separation, the heat conductivity can take place to descend. The heat conduction function of the pouring sealant cannot be normally exerted, so that the electronic device is damaged, the hidden trouble of circuit failure of the electronic component is caused, and even a fire disaster is caused in serious cases. On the other hand, the excessive addition of the inorganic filler can affect the toughness and the transparency of the pouring sealant, and the advantages of the organic silicon pouring sealant are lost.

CN109868113A discloses a motor potting adhesive, which is prepared by modifying mica sheets with nano graphene and a surfactant to obtain a heat-conducting filler, and then adding the heat-conducting filler into A, B components. On one hand, graphene is expensive and high in cost as a heat-conducting filler, and after the graphene is added, the graphene has certain electrical conductivity, so that the graphene is not suitable for being used as a pouring sealant. On the other hand, before the pouring sealant disclosed by the patent is cured, the viscosity reaches more than 5500mPa s, the flowability is poor, the tensile strength and the breaking strength are insufficient, and the pouring sealant has defects when being used as the pouring sealant.

CN104312529A discloses an organosilicon heat-conducting electronic pouring sealant and a preparation method thereof, wherein the pouring sealant comprises the following components: 100 parts of vinyl-terminated silicone oil, 9-20 parts of hydrogen-containing silicone oil, 2-5 parts of alkynyl cyclohexanol, 50-200 parts of alumina, 0.1-1.4 parts of KH570 and 0.0015-0.0025 parts of catalyst. The application amount of the aluminum oxide can be reduced after the aluminum oxide is modified by the silane coupling agent. In the prior art, CN102924924A and CN108047722A both adopt silane coupling agents to carry out surface modification on heat-conducting fillers, although the compatibility of inorganic fillers and organic silicon is improved to a certain extent, the compatibility is improved preferentially, particularly under the oxidation condition, the weather resistance is still insufficient, the heat conductivity is reduced after long-time placement, the heat dissipation effect cannot be exerted, the electric device is damaged, and even the potential safety hazard of fire is caused seriously.

Therefore, there is a need to develop an electronic potting adhesive with excellent comprehensive properties in terms of thermal conductivity, compatibility, weather resistance, optical properties, insulation properties, flame retardancy, etc. to meet the increasingly high requirements of electronic devices.

Disclosure of Invention

In order to solve the defects of poor compatibility and insufficient weather resistance of the pouring sealant caused by adding the inorganic heat-conducting filler in the prior art, the invention adopts the macromolecular coupling agent to modify the inorganic heat-conducting material, enhances the compatibility of the inorganic filler and the organic silicon, simultaneously reduces the using amount of the inorganic filler, maintains the light transmittance characteristic of the organic silicon, and can conveniently observe the use and working conditions of electronic components; meanwhile, the paint has excellent mechanical property and weather resistance, can be safely and stably used for a long time, and provides great convenience for industry.

The technical scheme provided by the invention is as follows: a heat-conducting type bi-component pouring sealant comprises a component A and a component B, wherein the component A comprises the following raw materials in parts by weight: 40-70 parts of vinyl silicone oil, 12-17 parts of modified heat-conducting filler, 8-15 parts of reinforcing filler, 0.5-1 part of catalyst, 0-11 parts of polyether modified silicone oil and 0-20 parts of dimethyl silicone oil; the component B comprises the following raw materials in parts by weight: 30-50 parts of vinyl silicone oil, 13-22 parts of hydrogen-containing silicone oil, 12-17 parts of modified heat-conducting filler, 6-11 parts of polyether modified silicone oil, 0.5-1 part of inhibitor, 0-11 parts of polyether modified silicone oil and 0-20 parts of dimethyl silicone oil; the condition is that in the A, B component, the total amount of the dimethyl silicone oil is 15-20 parts, and the total amount of the polyether modified silicone oil is 6-11 parts.

The modified heat-conducting filler is prepared from a macromolecular coupling agent and an inorganic heat-conducting filler, wherein the inorganic heat-conducting filler is selected from aluminum nitride and aluminum oxide, and the particle size D50 of the inorganic heat-conducting filler is 0.1-2 mu m, preferably 0.1-1 mu m.

The macromolecular coupling agent is a terpolymer of unsaturated carboxylic acid and/or ester thereof, and unsaturated polyether and double-bond-containing silane coupling agent as monomers.

Further, the unsaturated carboxylic acid is selected from (meth) acrylic acid, the ester is a lower alkyl ester of the unsaturated carboxylic acid, and the ester group is an ester group of C1-C6, such as methyl ester, ethyl ester, propyl ester, butyl ester.

The unsaturated polyether is selected from allyl polyoxyethylene ether, isoamyl alcohol polyoxyethylene ether and methallyl alcohol polyoxyethylene ether, and the molecular weight is 500-800 g/mol.

The double-bond-containing silane coupling agent is gamma-methacryloxypropyltrimethoxysilane, vinyl trimethoxysilane, vinyl tri (-methoxyethoxy) silane and vinyl triethoxysilane.

The ratio of the unsaturated carboxylic acid and/or ester thereof, unsaturated polyether and double bond-containing silane coupling agent is 6-9:2-4: 1-1.5.

The macromolecular coupling agent is prepared by the following method: three monomers were: unsaturated carboxylic acid and/or ester thereof, unsaturated polyether and silane coupling agent containing double bonds are fed according to the proportion and are copolymerized under the action of an initiator to obtain the polyether polyol.

The initiator and the amount thereof are not particularly limited, and the initiator for conventional radical polymerization may be, for example, peroxy, azo, redox initiation systems. Specifically, it may be selected from benzoyl peroxide, azobisisobutyronitrile, potassium persulfate-sodium bicarbonate. The amount of initiator used is generally from 0.2 to 0.5% by weight of the total mass of the monomers.

Further, the modified heat-conducting filler is prepared according to the following preparation method: adding dried inorganic heat-conducting filler, macromolecular coupling agent and solvent, firstly carrying out ultrasonic dispersion, heating and refluxing, after the reaction is finished, putting into methanol, washing the precipitate with methanol, drying, and grinding to obtain the product with the specified particle size. Preferably, the mass ratio of the inorganic heat-conducting filler to the macromolecular coupling agent is 1: 2.3-3.7.

The vinyl silicone oil has a vinyl content of 0.4-0.7% and a viscosity of 500-1000 mPas.

The hydrogen content of the hydrogen-containing silicone oil is 0.1-0.3%, and the viscosity is 200-500mPa & s.

The viscosity of the polyether modified silicone oil is 1200-1700 mPas.

The viscosity of the dimethyl silicone oil is 30-200 mPas, preferably 50-130 mPas.

The reinforcing filler is calcium carbonate. Preferably stearic acid modified calcium carbonate, D50 is 2-5 μm.

The catalyst is a conventional hydrosilylation platinum-containing catalyst, such as chloroplatinic acid, platinate salts, platinum and complexes containing alkenyl, carbonyl groups (platinum (0) -1, 3-divinyltetramethyldisiloxane complex, bis (ethylacetoacetate) platinate).

The inhibitor is an alkynol inhibitor, such as 3-methyl-1-butyn-3-ol, trimethyl-1-pentyn-3-ol, 3, 5-dimethyl-1-hexyn-3-ol, 1-ethynyl-1-cyclohexanol, and 3-phenyl-1-butyn-3-ol.

Optionally, various additives such as flame retardant, plasticizer, stabilizer, antioxidant, leveling agent and tackifier can be added into the two components. These components may be added to the A component or the B component individually, or to both the A component and the B component.

The invention also provides a preparation method of the heat-conducting type bi-component pouring sealant, which comprises the following steps:

preparation of component A: adding vinyl silicone oil and a reinforcing filler, stirring under a vacuum condition, adding the modified heat-conducting filler and a catalyst, heating to 100-120 ℃, continuing stirring for 1-2h, cooling, closing vacuum, adding dimethyl silicone oil and/or polyether modified silicone oil, and uniformly stirring to obtain a group A;

preparation of the component B: adding vinyl silicone oil, hydrogen-containing silicone oil, an inhibitor and a modified heat-conducting filler, heating to 120 ℃, stirring for 1-2h under a vacuum condition, cooling, closing the vacuum, adding dimethyl silicone oil and/or polyether modified silicone oil, and uniformly stirring to obtain the component B.

The heat-conducting type bi-component pouring sealant is convenient and quick to use, and only A, B components are required to be mixed according to the mass ratio of 1-1.2: 1-1.2, and can be rapidly cured and molded at room temperature. The cured mechanical property, weather resistance, thermal conductivity and light transmittance all can meet the requirements.

Compared with the prior art, the invention has the following beneficial effects:

according to the method, the using amount of the inorganic heat-conducting filler can be reduced, and the heat conductivity of the material after solidification is still excellent. The advantage of reducing the use amount of the inorganic heat-conducting filler also comprises that when the two components are mixed, the viscosity is not high, the leveling property is good, and the self-leveling effect can be achieved without adding a leveling agent; meanwhile, the addition amount of the inorganic filler is small, so that the light transmittance of the cured material is not obviously adversely affected, the molded material still keeps certain light transmittance, and the working condition of electronic components is conveniently observed.

Detailed Description

Allyl polyoxyethylene ether and isoamyl alcohol polyoxyethylene ether are purchased from Shanghai Taiwan chemical industry, and the number average molecular weight of the allyl polyoxyethylene ether is about 630 g/mol; the molecular weight of the isoamyl alcohol polyoxyethylene ether is about 750 g/mol.

Vinyl silicone oil was purchased from New Material Ltd of Santa Clara, Shandong, having an alkenyl group content of 0.6 wt% and a viscosity of 700 mPas. The hydrogen-containing silicone oil is purchased from New Material Co., Ltd of Santa Clara, Shandong, having an active hydrogen content of 0.2 wt% and a viscosity of 300 mPas. The polyether modified silicone oil is purchased from New materials of Santa Clara, Shandong, and has viscosity of 800 mPas. Dimethicone was purchased from Dow Corning and had a viscosity of 80 mPas.

Preparation example 1

Feeding methacrylic acid, allyl polyoxyethylene ether and vinyl trimethoxy silane according to a molar ratio of 8:3:1, adding toluene which is 2.3 times of the total mass of monomers as a solvent, heating to 80 ℃ under a nitrogen atmosphere for reflux, dropwise adding BPO accounting for 0.5 wt% of the total mass of the monomers, continuing to reflux for 4 hours after half an hour of dropwise adding, cooling, filtering, and drying in vacuum to obtain a macromolecular coupling agent, and adding toluene to prepare a 30 wt% solution.

Taking 10 parts of aluminum nitride, drying, adding 77 parts of 30 wt% of macromolecular coupling agent in toluene solution, ultrasonically dispersing for half an hour, heating to 80 ℃, refluxing for 3 hours, cooling, putting into methanol, washing the generated precipitate for several times by using the methanol, drying, and grinding in a ball mill until D50 is 1.5 mu m to obtain the modified aluminum nitride.

Preparation example 2

The other conditions and procedures were the same as in preparation example 1 except that no monomeric allyl polyoxyethylene ether was added.

Preparation example 3

The other conditions and procedures were the same as in preparation example 1, except that the monomer vinyltrimethoxysilane was not added.

Preparation example 4

The other conditions and procedure were the same as in preparation example 1, except that the monomers methacrylic acid, allyl polyoxyethylene ether and vinyltrimethoxysilane were charged in a molar ratio of 8:3: 0.5.

Preparation example 5

The other conditions and procedure were the same as in preparation example 1, except that grinding was carried out in a ball mill until D50 became 2.2 μm.

Example 1

Preparation of component A: preheating a double-planetary power mixing device to 60 ℃, adding 50 parts of vinyl silicone oil and 10 parts of stearic acid modified calcium carbonate, stirring under a vacuum condition, adding 12 parts of the modified heat-conducting filler prepared in preparation example 1 and 0 and 5 parts of chloroplatinic acid under a stirring condition, heating to 110 ℃, continuing stirring for 2 hours, cooling, closing vacuum, adding 8 parts of dimethyl silicone oil and 6 parts of polyether modified silicone oil, and uniformly stirring to obtain a component A;

preparation of the component B: adding 40 parts of vinyl silicone oil, 16 parts of hydrogen-containing silicone oil, 1 part of 3-methyl-1-butyn-3-ol and 12 parts of the modified heat-conducting filler prepared in the preparation example 1, heating to 110 ℃, stirring for 2 hours under a vacuum condition, cooling, closing vacuum, adding 8 parts of dimethyl silicone oil and 5 parts of polyether modified silicone oil, and uniformly stirring to obtain the component B.

Example 2

The other steps and conditions were the same as in example 1 except that the modified heat conductive filler obtained in preparation example 1 was replaced with the modified heat conductive filler obtained in preparation example 2.

Example 3

The other steps and conditions were the same as in example 1 except that the modified heat conductive filler obtained in preparation example 1 was replaced with the modified heat conductive filler obtained in preparation example 3.

Example 4

The other steps and conditions were the same as in example 1 except that the modified heat-conductive filler obtained in preparation example 1 was replaced with the modified heat-conductive filler obtained in preparation example 4.

Example 5

The other steps and conditions were the same as in example 1 except that the modified heat-conductive filler obtained in preparation example 1 was replaced with the modified heat-conductive filler obtained in preparation example 5.

Example 6

The other steps and conditions were the same as in example 1 except that the amount of the polyether-modified silicone oil in the A component was 3 parts and the amount of the polyether-modified silicone oil in the B component was 3 parts.

Comparative example 1

The other steps and conditions were the same as in example 1 except that the modified thermally conductive filler in the a-component and the B-component was replaced with aluminum nitride having the same particle size, i.e., the thermally conductive filler was not modified.

Comparative example 2

The other steps and conditions were the same as in example 1 except that the A-component and the B-component did not contain the polyether-modified silicone oil.

Application example

The two-component potting adhesives of the examples and the comparative examples are prepared according to the following components: and mixing the component B in a mass ratio of 1:1, and curing for 24-72h at room temperature to obtain the cured and molded pouring sealant. The following tests were performed. The results are shown in table 1 below:

the viscosity is tested when the A component and the B component are quickly and uniformly mixed, and the leveling property of the pouring sealant can be represented.

The insulation property is that the breakdown voltage is larger than 22kV/mm

Weather resistance test, (a) low temperature resistance: standing at-40 deg.C for cracking or powdering time (d, day); (b) the time for cracking or chalking under the irradiation of 300W ultraviolet light; (c) time to cracking or chalking at 120 ℃.

TABLE 1 encapsulation performance test table

The applicant states that the present invention is illustrated by the above examples to show specific reagents, equipment and process flows of the present invention, but the present invention is not limited to the above specific reagents, equipment and process flows, i.e. it does not mean that the present invention must rely on the above reagents, equipment and process flows to be carried out. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims

1. A heat-conducting two-component pouring sealant comprises a component A and a component B, wherein the component A comprises the following raw materials in parts by weight: 40-70 parts of vinyl silicone oil, 12-17 parts of modified heat-conducting filler, 8-15 parts of reinforcing filler, 0.5-1 part of catalyst, 0-11 parts of polyether modified silicone oil and 0-20 parts of dimethyl silicone oil; the component B comprises the following raw materials in parts by weight: 30-50 parts of vinyl silicone oil, 13-22 parts of hydrogen-containing silicone oil, 12-17 parts of modified heat-conducting filler, 0.5-1 part of inhibitor, 0-11 parts of polyether modified silicone oil and 0-20 parts of dimethyl silicone oil; the conditions are that in the A, B component, the total amount of the dimethyl silicone oil is 15-20 parts, and the total amount of the polyether modified silicone oil is 6-11 parts; the modified heat-conducting filler is prepared from a macromolecular coupling agent and an inorganic heat-conducting filler; the macromolecular coupling agent is a terpolymer of unsaturated carboxylic acid and/or ester thereof, and unsaturated polyether and double-bond-containing silane coupling agent as monomers.

2. A heat conductive two component potting adhesive as claimed in claim 1, wherein the inorganic heat conductive filler is selected from the group consisting of aluminum nitride, aluminum oxide; the particle diameter D50 of the inorganic heat-conducting filler is 0.1-2 μm.

3. A heat-conductive two-component potting adhesive as claimed in claim 2, wherein the particle size D50 of the inorganic heat-conductive filler is 0.1 to 1 μm.

4. A heat conductive two-component potting adhesive as claimed in claim 1, wherein the unsaturated carboxylic acid is selected from (meth) acrylic acid, the ester is a lower alkyl ester of the unsaturated carboxylic acid, the lower alkyl ester is an ester group of C1-C6;

the unsaturated polyether is selected from allyl polyoxyethylene ether, isopentenol polyoxyethylene ether or methallyl alcohol polyoxyethylene ether, and the molecular weight is 500-800 g/mol;

the double-bond-containing silane coupling agent is gamma-methacryloxypropyltrimethoxysilane, vinyl trimethoxysilane, vinyl-tri (2-methoxyethoxy) silane and vinyl triethoxysilane.

5. A heat-conductive two-component potting adhesive as claimed in claim 1, wherein the mass ratio of the unsaturated carboxylic acid and/or ester thereof, unsaturated polyether and double bond-containing silane coupling agent is 6-9:2-4: 1-1.5.

6. A heat conductive two-component potting adhesive as claimed in claim 1, wherein the modified heat conductive filler is prepared by the following preparation method: adding dried inorganic heat-conducting filler, macromolecular coupling agent and solvent, firstly carrying out ultrasonic dispersion, heating and refluxing, after the reaction is finished, putting into methanol, washing the precipitate with methanol, drying, and grinding to obtain the product with the specified particle size.

7. A heat-conducting two-component pouring sealant as claimed in claim 6, wherein the mass ratio of the inorganic heat-conducting filler to the macromolecular coupling agent is 1: 2.3-3.7.

8. A heat-conductive two-component pouring sealant as claimed in claim 1, wherein the vinyl silicone oil has a vinyl content of 0.4-0.7%, a viscosity of 500-1000mPa · s; and/or

The hydrogen content of the hydrogen-containing silicone oil is 0.1-0.3%, and the viscosity is 200-500mPa & s; and/or

The viscosity of the polyether modified silicone oil is 1200-1700mPa & s; and/or

The viscosity of the dimethyl silicone oil is 30-200 mPa.

9. A heat-conductive two-component potting adhesive as claimed in claim 8, wherein the viscosity of the dimethylsilicone fluid is 50 to 130mPa · s.

10. A heat conductive, two-component potting adhesive as claimed in claim 1, wherein the reinforcing filler is calcium carbonate.

11. A heat conductive two component potting adhesive as claimed in claim 10, wherein the reinforcing filler is stearic acid modified calcium carbonate and D50 is 2-5 μm.

12. The preparation method of the heat-conducting two-component pouring sealant of any one of claims 1 to 11, comprising the following steps:

13. The use of the heat-conducting two-component potting adhesive of any one of claims 1 to 11 in the bonding, sealing, potting and coating protection of electronic components, characterized in that A, B components are mixed according to the mass ratio of 1-1.2: 1-1.2, and curing and forming.